Casing for limiting the clearance of the strands of a sling and slings utilizing such casings



March 1967 JEAN-FRANCOIS ARCHER 3,

; CASING FOR LIMITING THE'CLEARANCE OF THE STRANDS v OF A SLING AND SLINGS-UTILIZING SUCH GASINGS FilGd 001.. 23, 1964 2 Sheets- Sheet 1 "I /g1 v 7 H93 i Eg IN VEN TOE Jsm'v- Fen/V9015 ARCH/52 A r okws Y5 United States Patent Ofitice 3,307,870 Patented Mar. 7, 1967 3,307,870 CASING FOR LIMITING THE CLEARANCE OF THE STRANDS OF A SLING AND SLINGS UTI- LIZING SUCH CASINGS Jean-Francois Archer, Hameau des Perdrix, La Celle-Saint-Cloud, France Filed Oct. 23, 1964, Ser. No. 406,070 Claims priority, application France, Nov. 4, 1963, 9 ,553 6 Claims. (Cl. 204-74) In order to produce a sling with at least two strands, intended for lifting various loads, a closed ring is generally used, on which are freely fixed as many cables as the sling under consideration has strands. One of the ends of each cable is then connected in the ring, folded back against said cable in order to form a loop and secured to the said cable by means of an inset sleeve.

While a sling of this type is being used, the ring is threaded onto the hook for lifting purposes. Now, in the case where the load to be moved is very heavy, the dimensions of said hook are reltaively large and, consequently, the internal diameter of the ring of a suitable sling is itself large. Moreover, since said ring must not become twisted under the action of the lifted load, the section of the said ring grows to large proportions, since it depends as is well known, on the load, and on the average diameter of the ring. A ring of this type is thus difficult to produce. In any case, it is very heavy, thus diificult to manipulate and its cost price is very high.

According to the present invention, the ring of such a sling is removed and replaced by a closed loop, produced in the median part of a single cable, constituting said sling. The strands of the sling extending on both sides of the median loop are connected to the edge of said latter by means of an inset sleeve of a known type. This connection is inadequate, since the strands, when they are hooked to a load, are sloping, in order to ensure the stability of the load. By reason of said inclination of the strands, the sleeve is attracted by opposite, horizontal forces tending to open it.

The present invention relates thus to a casing provided for covering the inset sleeve, said casing being formed, on the one hand, to constitute a hoop for securing the said sleeve and, on the other hand, to limit the clearance of the strands of the sling. In fact, it is important that said clearance does not exceed an angular opening for securing, beyond which the tension in the strands of the sling is out of proportion in respect of the weight of the hooked load at the end of said strands and beyond which the stability of the said load is comprised in certain attachment conditions.

According to the invention, the casing has an axial bore in the form substantially complementary to the inset sleeve, the bore being connected to the exterior by means of two conduits progressively diverging towards the end of the said casing on which they emerge.

According to one particularly advantageous embodiment, the axial bore of the casing is cylindrically truncated for the arrangement of an inset cylindrical sleeve, said bore being connected, on the one hand, in discontinuity of form, to an inlet conduit, the oval section of which extends more and more, as the divergence of the said inlet conduit is accentuated more, and, on the other hand, by means of a locking shoulder for the sleeve, to an outlet conduit, the size of which is constant but the length of which grows as the divergence of the said outlet conduit is accentuated.

In other respects, the casing co-operates with a removable rod traversing the walls of said casing located opposite the smallest part of the inlet conduit.

The present invention extends in other respects to the new industrial product, constituted by a sling with two strands, characterised in that a loop is formed in the median part of a single cable and in that the strands ex tending on both sides of said loop are connected to the edge of said latter by an inset sleeve covered by a casing, the removable rod of which crosses the said loop. v

By means of these characteristics, an appreciable saving is made on the weight of a sling and on its price. Another advantage of a sling of this type is in the fact that said latter may be used with a single strand working in the same way as a simple sling. Another particularly important advantage concerns the security of use which, due to the invention, is improved. In fact, in a conventional sling with two strands, there are three possible rupture zones localised in the ring and in the two inset sleeves provided for forming the loops of the two cables threaded on the rings. On the other hand, in the sling of the invention with two strands, the risk of rupture is localised in one zone, name-1y the sleeve closing the single loop. In other respects, in this case, the probability of rupture is less than for a conventional sling, since the presence of a casing increases the resistance of the assembly.

The present invention finally extends to the new industrial products constituted by a sling with four strands, which is produced by means of two slings with two strands, the loops of which intersect. Under the effect of the load which said sling supports, the four strands are put under tension and the two opposite, horizontal components of the tensions thus produced, tend to apply the two loops one against the other on their upper part, due to the fact that they intersect and consequently, tend to keep them in the hollow of the lifting hook. It is evident that said sling with four strands has the same advantages as those stated for the sling with two strands.

In order that the invention may be more clearly understood, reference will now be made to the accompanying drawings which show some embodiments thereof by way of example and in which:

FIGURE 1 shows an elevation of a face of a casing according to the invention, said elevation, partially in section, being shown along the line II of FIGURE 2, which is a plan, shown from above, of the said casing,

FIGURE 3 is a side elevation of said casing,

FIGURE 4 is an elevation illustrating a sling with two strands according to the invention, and

FIGURE 5 is a partial perspective view showing a sling with four strands according to the invention.

Referring to the drawings, a casing 1 is formed by a single part having a great mechanical resistance; it is constituted preferably by an aluminium alloy which, besides its resistance, has the advantage of being practically invulnerable in the usual conditions of use. It may also be of steel of another metal alloy, rust-proof or rendered such by any suitable treatment.

The casing 1 has an axial bore 2, the shape of which is substantially complementary to that of an inset sleeve, provided for connecting the two strands of a cable in the manner hereinafter described. In the example shown, the bore 2 comprises a cylindrical part 3 and a gradually tapered or truncated part 4, and is intended to constitute a housing for an inset sleeve of substantially cylindrical shape. As shown, the truncated part 4 decreases gradually in size from a point spaced from the inlet end of the bore 2 to the outlet end thereof. Under these conditions, the casing 1 constitutes a hoop for radially securing the said sleeve.

The bore 2 is connected to the exterior by means of two conduits 5 and 6 diverging progressively towards the ends 7 and 8 of the said casing on which it emerges. The conduits 5 and 6 are intended to limit the clearance of the hereinabove mentioned strands of cable, so that the angular opening of the said strands is lower than a limit of security determined by experience.

As FIGURES l and 2 clearly show, the inlet conduit 5 has an oval section 9, the size of which is equal to the diameter of the cylindrical part 3 of the bore 2 but the extension of which increases as the divergence of the said inlet conduit towards the exterior is accentuated. Moreover, the most divergent parts of the inlet conduit 5 have :urved lines of contact, the tangents of which, located in the plane of symmetry of the casing (corresponding the plane of the section) and near the end 7, make be- ;ween them an angle equal to the maximum admissible angle which the strands of a hereinafter described loop rnust form. The radius of curvature of the directrices (oval sections) of the inlet conduit is at least equal, in :he most divergent parts, to that of the radius of the original cable.

While the connection between the bore 2 and the inlet :onduit 5 is produced without discontinuity of form, the :onnection of said bore with the outlet conduit 6 is effected by means of a shoulder 10 provided to constitute 1 locking element, against which the inset sleeve referred :o rests. The outlet conduit 6 has a flat section 11, the ends 12, 13 of which are rounded. The size of said out- .et conduit is constant and substantially equal to the diam- :ter of the cable, while its length increases as the divergence of the said outlet conduit is accentuated. The ihoulder 10 then corresponds to the surface which exists n the circular section of the truncated part 4 of the bore 2, once the flat section of the conduit 6 has been deduced. The lines of contact of the rounded ends 12 and 13 of :he conduit 6 are curved and their tangents, located in :he plane of symmetry of the casing and near the end 5, form between them an angle equal to the angle of op- ;imum clearance of the strands of the cable, on which 1 load may be suspended. Moreover, the radius of curvature of the ends 12 and 13 is substantially equal to the radius of the said cable.

From the preceding description, it will be seen that the :asing 1 constitutes:

an the one hand, a hoop for an inset sleeve arranged in the bore 2 and resting against the shoulder 10,

)n the other hand, an element limiting the clearance for the two strands of cable connected by the said sleeve, by the fact that there exists in said casing a diverging inlet conduit 5 corresponding to the strands of a loop formed in the cable and a divergent conduit corre sponding to the free strands of the cable.

It is evident that the casing may have any external shape from the moment when its mechanical resistance .s sufficient. In the example illustrated in the drawing, :he casing is barrel-shaped but truncated along two planes parallel to its axis.

Finally, a hole 14 is made in the walls of the casing, :hese walls being located opposite the smallest part of the inlet conduit 5. This hole is intended to act as a location for a removable rod such as a pin, a bolt or the Like, in order that said rod crosses the said conduit be- :ween the two strands of the loop formed in the cable. Thus one is certain that the casing 1 will remain in place around the inset sleeve, since if it tended to slide, its rod 14 would rest against the sleeve and would support it.

The present invention has as an object, not only the :asing limiting the clearance previously described, but also the new industrial product constituted by a sling embodying at least one casing of this type.

FIGURE 4 shows a sling with two strands 15 which may be made in a single cable. For this purpose, a loop 16 is formed in the median part of the cable and is closed by means of a cylindrical inset sleeve 17. The loop is intended to be threaded on a lifting hook, the two strands 1S and 19 of the sling being constituted by the parts of the cable extending on both sides of said loop. According to the invention, the inset sleeve 17 is covered by a casing 20 in the holes 14 of which a bolt 21 is located, the rod of which crosses the loop 16.

FIGURE 5 shows a sling with four strands 22 which may be formed in the following manner. It is constituted by two slings with two strands 23 and 24 identical to that illustrated in FIGURE 4, slings of which the median loops 25, 26 respectively intersect, so that they may be held one against the other. Said loops are intended to be threaded on a hook 27. When a load is suspended from four strands 28 to 31, the two horizontal components of the tensions thus produced in the hereinabove described strands, are opposite and located in the plane of the hook. They tend to apply the two loops 25 and 26 one against the other, at their upper part, due to the fact that said latter intersect and consequently, they tend to return and keep the two loops in the hollow of the lifting hook 27 The invention is not limited to the embodiment of the casing and to the examples of application shown and described in detail, since various modifications may be added thereto without extending its scope as defined by the appended claims.

I claim:

1. A casing with limited clearance for the two strands of a cable connected by an inset sleeve, said casing being axially bored, the bore being substantially cylindrical in order to constitute a confining hoop for slidably and removably receiving an inset sleeve and relieving lateral strain thereon, said bore being connected on one end, without discontinuity of form, to the exterior of said casing by means of an inlet conduit which emerges into an oval section for limiting the inlet clearance of the strands of an encased cable, said bore being connected on the other end to the exterior of said casing by an outlet conduit, the width of the inner end of said outlet conduit being less than the shortest distance across said other end of said bore whereby the inner end of the outlet conduit constitutes a locking shoulder providing a rest for an inset sleeve disposed in said bore, said outlet conduit emerging into a substantially oval section in order to limit the outlet clearance of the strands of an encased cable.

2. A casing according to claim 1 wherein said axial bore decreases gradually in size throughout its length from a point spaced from the inlet end to the outlet end thereof thereby providing a socket for a substantially cylindrical inset sleeve, and the width of the outlet conduit is constant in cross-section but the length thereof grows as the divergence of said outlet conduit increases.

3. A sling comprising a pair of cables, each cable being bent back upon itself to form a closed loop intermediate the opposite ends thereof, the cable forming the loop of one cable passing through the loop of the other cable thereby linking said loops together, an inset sleeve conmeeting the strands of each cable together at the edge of the respective loop, a casing having an axial bore substantially complementary to the shape of the outer surface of the corresponding inset sleeve slidably and removably enclosing the corresponding sleeve, the bore of each casing being connected on one end, without discontinuity of form, to the exterior of the casing by means of an inlet conduit which emerges into an oval section, the bore of each casing being connected on the other end to the exterior of said casing by an outlet conduit which emerges into a substantially oval section, the Width of the inner end of each of said outlet conduits being less than the shortest distance across said other end of the respective bore whereby the inner end of the outlet conduit of each casing constitutes a locking shoulder for the enclosed inset sleeve, and two removable rods, one removable rod passing between the strands of a respective looped cable and through the walls of the inlet conduit of its corre-- sponding casing, each of said rods being disposed normal to the length of the respective oval section and located intermediate the opposite ends of the corresponding oval section, said rod retaining said inset sleeve in said axial bore.

4. A casing according to claim 1, wherein the most divergent parts of said inlet and outlet conduits are arranged symmetrically with respect to the diametrical plane of said bore, the lines of contact of said parts being curved and their directrices having a radius of curvature at least equal to the radius of an encased cable.

5. A casing according to claim 1, wherein the casing has a removable rod passing through the walls of said casing located opposite the smallest part of said inlet conduit.

6. A casing according to claim 5, forming part of a sling which further includes two strands, corresponding References Cited by the Examiner UNITED STATES PATENTS 2,551,803 5/1951 Leonard 294-74 X FOREIGN PATENTS 722,074 '6/ 1942 Germany.

GERALD M. FORIJENZA, Primary Examiner.

to the two parts of a single cable extending on both sides 15 ABRAHAM Assistant Examiner 

1. A CASING WITH LIMITED CLEARANCE FOR THE TWO STRANDS OF A CABLE CONNECTED BY AN INSET SLEEVE, SAID CASING BEING AXIALLY BORED, THE BORE BEING SUBSTANTIALLY CYLINDRICAL IN ORDER TO CONSTITUTE A CONFINING HOOP FOR SLIDABLY AND REMOVABLY RECEIVING AN INSET SLEEVE AND RELIEVING LATERAL STRAIN THEREON, SAID BORE BEING CONNECTED ON ONE END, WITHOUT DISCONTINUITY OF FORM, TO THE EXTERIOR OF SAID CASING BY MEANS OF AN INLET CONDUIT WHICH EMERGES INTO AN OVAL SECTION FOR LIMITING THE INLET CLEARANCE OF THE STRANDS OF AN ENCASED CABLE, SAID BORE BEING CONNECTED ON THE OTHER END TO THE EXTERIOR OF SAID CASING BY AN OUTLET CONDUIT, THE WIDTH OF THE INNER END OF SAID OUTLET CONDUIT BEING LESS THAN THE SHORTEST DISTANCE ACROSS SAID OTHER END OF SAID BORE WHEREBY THE INNER END OF THE OUTLET CONDUIT 